Quote:
Originally Posted by chetrickerman
You are completely correct. On my old car, (Evo X) I built a 2.4L stroker with forged everything and a dry sump oil system. The dry sump belt came off after a WOT pull and of course the motor lost oil pressure. I shut it down about 2 seconds after the belt came off and I thought I caught it in time.
I sent in an oil analysis on that same oil to see if the bearings showed any wear on the UOA. The UOA came back completely normal, yet a couple hundred miles later, before I sold the motor I pulled all the bearings just to make sure they were good and the bearings were trashed.
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Thank you. I still read lots on UOAs and how they are useful. But we are well over a decade of pretty commonly conducted UOAs across tons of platforms. And you know what?
They are terrible at diagnosing problems outside of the following:
1. An issue causing excessive fuel accumulation in the oil (i.e. stuck injector) which will almost always show up via CEL on any OBDII system
2. An issue with air filtration whereby filtration isn't as good as it should be - which can be useful
3. Determining if you are driving your oil into sludge or if it can keep going
....
And you know who needs this? Not people who change their oil every 5k-10k miles on newer vehicles using synthetic oils.
Let me repeat this to the general public: A UOA will not be a reliable tool to diagnose metal-on-metal wear problems with your engine in a preventative fashion. It MAY diagnose fuel issues dumping fuel into your cylinder/oil, air filtration issues, or determining if your oil is worn out (extremely rare with synthetic oils run normal durations).
That's it - if you aren't looking to diagnose those things, skip the UOA.